US 2004/0046860 A1 discloses a laser printer comprising a two-dimensional array of vertical-cavity surface-emitting lasers (VCSELs) and an optical imaging unit for imaging the two-dimensional array of VCSELs onto a working plane. The optical imaging unit needs to be technically relatively complex and to have relatively large dimensions, in order to provide high quality imaging without significant optical aberrations as needed for high quality laser printing.